#include <cstdio>
#include <vector>

using namespace std;

vector <int> V;
vector<vector<int>> h;

void hist (vector<int> VV) {
	//vector <vector<int>> h;
	h.clear();
	for (int i = 0; i < 32; i++)
		h.push_back(vector<int>());

	for (auto i : VV) {
		for (int j = 0; j < 32; j++) {
			if (i & (1 << j))
				h[j].push_back(i);
		}
	}

	//return h;
}

int main () {
	int n, k;

	scanf("%d %d", &n, &k);
	for (int i = 0; i < n; i++) {
		int x;
		scanf("%d", &x);
		V.push_back(x);
	}

	hist(V);
	int r= 0;

	for (int i = 31; i > 0; i--) {
		if (h[i].size() >= k) {
			hist(h[i]);
			for (int j = 31; j >= 0; j--)
				if (h[j].size() >= k)
					r += (1 << j);
			break;
		}
		
	}

	printf("%d\n", r);
}